Process of producing blue prints



(No Model.)

J. G. ELDER.

PROCESS OF PRODUCING BLUE PRINTS. No. 368,656. PatentedAug. 23, 1887.

Y 5WIIllIIIIIIlIl/lIIIIIIIIIIIIIIIIIIIIIIII/IlIlI/IIIII/IIIII/IlI/IIlIIlI/IIWITNESSES 6 uvvnvrop UNITED STATES PATENT UEEicE.

JAMES C. ELDER, OF JEFFERSON, ASSIGNOR, BY DIRECT AND MESNE ASSIGN-MENTS, TO THE AMERICAN ETCHING AND ENGRAVING COMPANY, OF

CHICAGO, ILLINOIS.

PROCESS OF PRODUCING BLUE PRINTS.

SPECIFICATION forming part of Letters Patent No. 368,656, dated August23, 1887.

Application filed July 24, 185. Serial No. 172,510. (No modeld T crZZwhom, it may concern.-

Be it known that 1, JAMES C. ELDER, a citizen of the United States,residing at Jefferson, in the county of Cook and State of Illinois,'haveinvented certain new and useful Improvements in the Process or- Art ofMaking Photographic Negatives, which are fully set-forth in thefollowing specification, reference being had to the accompanyingdrawings,

forming a part hereof.

My invention has relation to the manufacture of negatives for use inmaking sunprints; and it consists in a negative plate for such purposecomposed of a transparent plate 1 having applied thereto a coating ofopaque material covered with a coating of light pigment of coloredmaterial in such a manner that a pencil, pen,or other similar instrumentmay be employed to mark on such light "or white pigment, and by whichthe drawings made thereon may be altered without interfering with orinjuring the black undercoating, which must be thin and perfect, so asto give a clear-cut line without ragged edge to the print, and incertain steps in the art of making sun-prints by first coating a plateof transparent material with a dark-colored pigment; superposingacoating of light-colored pigment; delineating lines upon the upper 0coating; cutting through both of said coatings on the lines delineated;subjecting prepared paper to the action of light through the plate, and,finally, washing the same in the usual manner, all as hereinafterdescribed, and par- 5 ticularly pointed out in the claims. By thisprocessapencil-sketch, when drawn to satisfaction, may be transferredupon the white coating, or may be drawn thereon,which saves much timeand redrawing, and which facilio tates and cheapens the work.

Heretofore when the drawings were made on the single black pigment orcoating, if a mistake were made it could not be cured, and thus thenegative plate was destroyed; but

5 with my process the lines may be changed several times until they arecorrect, when they maybe etched or cut through the black coat ing byproper instruments. The plate is then ready for use.

In the accompanying drawings, Figure l is a sectional view through atransparent plate having the opaque or dark coating and a portion of thelight-colored coating applied thereto. Fig. 2 is a plan view of a platehaving the dark and light coatings applied and a drawing etched throughsaid coatings, parts of said coatings being removed. Fig. 3 is a planView of a sun-print made from the negative as shown in Fig. 2; and Fig.4 is a section on line 00 a: of Fig. 2.

Like letters of reference mark the same parts wherever they occur in thedifferent figures of the drawings.

Referring specifically to the drawings by letters of reference, a is atransparent plate, preferably of glass, although it may be made of anysuitable transparent material.

b is a coating superposed thereon, composed of any suitable opaquematerial, preferably a black pigment, applied by running it on, orapplying it in any other suitable mannor.

0 is a coating of light colored material, preferably a whitepigment-such as Chinese white-placed upon the dark coating, as shown. 75

WVhen a plate has been prepared by superposing,as described andshown,the opaque and light-colored pigments,a drawing may be made uponit with ink or pencil, and the said lines,

or the portions of the coatings covered by SC said lines, are removedwith suitable etching or engraving tools, leaving those portions of thetransparent plate clean to permit the pasages of the rays of the lighttherethrough.

To make a sun-print, an ordinary sheet of sensitive photographcpapersuch, for instance, as is used in making the well-known blueprints-is covered by such plate and exposed a proper length of time tothe rays of the light, preferably the suns rays, and then 0 removed, theprint being fixed by any suitable and well known process; if theblueprint process, the paperis thoroughly washed, leaving the lines ofthe drawing blue and the rest of the sheet white.

Having thus described my invention, what I claim, and desire to secureby Letters Patent of the United States, is-=- 1. As a new article ofmanufacture, a transparent plate having an opaque coating suitable foruse in making sun-prints, and upon such opaque coating a light coatingsuitable for the delineation of forms, all as set forth, whereby adrawing may be made and amended without detriment to the opaque coating,and whereby when both coatings are cut on the lines a sun-print may bemade in the usual manner.

'2. As an improvement in the art of making sun-prints, preparing atransparent plate by coating it with an opaque material of a charactersuitable for removal by a graver or other usual means, and covering saidopaque coat with a light-colored coat suitable for the delineationthereupon of lines preparatory to the cutting of both coatings uponsaidlines.

3. The process herein described for producing blue prints, whichconsists in first coating a plate of transparent material with adark-colored pigment, then superposing another coating of light-coloredpigment upon the first, thereby presenting an erasable drawing-surface,then delineating the desired sketch or drawing upon the top coating andcutting through both of said coatings on the lines of the drawing, so asto expose the clear surface of the plate, then subjecting prepared paperfor the usual print process to the action 0f 0 the'light through theplate, and finally washing the same in the usual manner, substantiallyas described.

JAMES C. ELDER.

Witn esses WM. ZIMMERMAN, A. H. RINTELMAN.

